Quantifying telomere length:from bulk assays to single-molecule resolutionOA

Telomere length(TL)is a promising biomarker for age-associated diseases and cancer.Single-molecule studies of human TL are advancing rapidly,providing unprecedented insights into the dynamics and variability of telomeres at the single-molecule level.TL is commonly reported as average TL or relative TL,depending on the methods used.However,average TL,short TL,and long TL have distinct significances:average TL serves as a general biomarker for aging,short TL indicates the risk of age-related diseases,and long TL is associated with certain cancers and all-cancer mortality.Thus,the TL distribution is more important than the average TL alone.Single-molecule techniques measure TL one telomere at a time,offering quantitative TL distributions that are crucial for understanding telomere biology.In this review,we focus on various TL measurement techniques,with particular emphasis on single-molecule methods.Single-molecule studies of human TL are poised to play a pivotal role in advancing our understanding and clinical management of age-associated diseases and cancer.